|.\" Hey, EMACS: -*- nroff -*-
|.TH DWEBP 1 "June 23, 2016"
|dwebp \- decompress a WebP file to an image file
|.RI [ options ] " input_file.webp
|This manual page documents the
|\fBdwebp\fP decompresses WebP files into PNG, PAM, PPM or PGM images.
|The basic options are:
|Print usage summary.
|Print the version number (as major.minor.revision) and exit.
|.BI \-o " string
|Specify the name of the output file (as PNG format by default).
|Using "-" as output name will direct output to 'stdout'.
|.BI \-\- " string
|Explicitly specify the input file. This option is useful if the input
|file starts with an '\-' for instance. This option must appear \fBlast\fP.
|Any other options afterward will be ignored. If the input file is "\-",
|the data will be read from \fIstdin\fP instead of a file.
|Change the output format to uncompressed BMP.
|Change the output format to uncompressed TIFF.
|Change the output format to PAM (retains alpha).
|Change the output format to PPM (discards alpha).
|Change the output format to PGM. The output consists of luma/chroma
|samples instead of RGB, using the IMC4 layout. This option is mainly
|for verification and debugging purposes.
|Change the output format to raw YUV. The output consists of
|luma/chroma-U/chroma-V samples instead of RGB, saved sequentially as
|individual planes. This option is mainly for verification and debugging
|Don't use the fancy upscaler for YUV420. This may lead to jaggy
|edges (especially the red ones), but should be faster.
|Don't use the in-loop filtering process even if it is required by
|the bitstream. This may produce visible blocks on the non-compliant output,
|but it will make the decoding faster.
|.BI \-dither " strength
|Specify a dithering \fBstrength\fP between 0 and 100. Dithering is a
|post-processing effect applied to chroma components in lossy compression.
|It helps by smoothing gradients and avoiding banding artifacts.
|If the compressed file contains a transparency plane that was quantized
|during compression, this flag will allow dithering the reconstructed plane
|in order to generate smoother transparency gradients.
|Disable all dithering (default).
|Use multi-threading for decoding, if possible.
|.BI \-crop " x_position y_position width height
|Crop the decoded picture to a rectangle with top-left corner at coordinates
|(\fBx_position\fP, \fBy_position\fP) and size \fBwidth\fP x \fBheight\fP.
|This cropping area must be fully contained within the source rectangle.
|The top-left corner will be snapped to even coordinates if needed.
|This option is meant to reduce the memory needed for cropping large images.
|Note: the cropping is applied \fIbefore\fP any scaling.
|Flip decoded image vertically (can be useful for OpenGL textures for instance).
|\fB\-resize\fR, \fB\-scale\fI width height\fR
|Rescale the decoded picture to dimension \fBwidth\fP x \fBheight\fP. This
|option is mostly intended to reducing the memory needed to decode large images,
|when only a small version is needed (thumbnail, preview, etc.). Note: scaling
|is applied \fIafter\fP cropping.
|If either (but not both) of the \fBwidth\fP or \fBheight\fP parameters is 0,
|the value will be calculated preserving the aspect-ratio.
|Do not print anything.
|Print extra information (decoding time in particular).
|Disable all assembly optimizations.
|Please report all bugs to the issue tracker:
|Patches welcome! See this page to get started:
|dwebp picture.webp \-o output.png
|dwebp picture.webp \-ppm \-o output.ppm
|dwebp \-o output.ppm \-\- \-\-\-picture.webp
|cat picture.webp | dwebp \-o \- \-\- \- > output.ppm
|\fBdwebp\fP is a part of libwebp and was written by the WebP team.
|The latest source tree is available at
|This manual page was written by Pascal Massimino <email@example.com>,
|for the Debian project (and may be used by others).
|.SH SEE ALSO
|.BR cwebp (1),
|.BR gif2webp (1),
|.BR webpmux (1)
|Please refer to http://developers.google.com/speed/webp/ for additional
|.SS Output file format details